U.S. Pat. No. 4,666,231, assigned in common with the present application, discloses a coaxial jack which is constructed for slidable assembly. The jack disclosed therein includes an inner contact, an intermediate contact, and a disconnect switch with switch pole contacts. Upon insertion of an insulative sleeve into the jack, the disconnect switch is activated.
In U.S. Pat. No. 4,628,159, a jack adapted for mounting on a printed circuit board and a plug for mating with the jack are disclosed. The jack includes a housing and a plurality of contacts for conducting electrical current. An insulating member is provided to support the contacts and to insulate them from each other. The jack further includes a switching mechanism for switching between a pair of the conducting contacts.
The plug of U.S. Pat. No. 4,628,159 is used for connecting shielded, twisted pair cable to the jack. The plug includes a housing, a central conductor, an intermediate conductor, and a dielectric member supporting and separating the two conductors. The dielectric member projects beyond the end of the housing. When inserted into the jack, the central conductor and the intermediate conductors of the plug engage corresponding contacts of the jack. At the same time, the dielectric member activates the switching mechanisms in the jack.
The central conductor of the plug described in U.S. Pat. No. 4,628,159 comprises a thin shaft and a cylindrical enlargement or gland with a flat side along the shaft. This central conductor is difficult to manufacture. In order to form the central conductor, it is necessary to start with a large piece of material due to the size of the gland. Moreover, several operations are necessary to form the central conductor. It is necessary to first draw out the shaft portion of the central conductor. The cylindrical gland is next formed by screw machining or some other turning process. The flat side of the gland is then formed by a final machining process.
The dielectric member of the plug described in U.S. Pat. No. 4,628,159 is also difficult to manufacture. It comprises a generally cylindrical body having an axial passage for receiving the central conductor, and a pair of circumferential inner passageways for receiving spaced apart contact members of the intermediate conductor. The dielectric member further includes a resilient arm. When the plug is mated with the jack, a portion of the jack forces the arm downward. The arm engages an edge of the intermediate conductor thereby locking the intermediate conductor in place.
The dielectric member is formed from a thermoplastic material in an injection molding process. The main body of the dielectric member is formed by pulling the mold in a single direction. However, in order to form the latching arm, it is necessary to pull the mold in a second direction, i.e., side action is required. This makes the manufacture of the dielectric member more difficult than it should be. Furthermore, the design of the dielectric member is not entirely satisfactory because it is undesirable to lock a metallic member, i.e., the intermediate conductor, in place by pressing an insulating material against a metallic piece. It is much more desirable, because of its strength, to provide a metallic arm which presses against an edge of the dielectric member.
Accordingly, it is an object of the invention to provide a switch activating plug having an inner conductor, an intermediate conductor, and a dielectric member which are adapted for slidable interengagement, wherein the inner conductor does not have an enlarged gland.
It is a further object of the invention to provide such a plug wherein the dielectric member does not include a resilient latching arm for locking the intermediate conductor in place.
It is a further object of the invention to provide such a plug wherein the dielectric member extends beyond the housing of the plug to activate a switch when the plug is mated with a jack.
It is yet another object of the invention to provide such a plug wherein the inner conductor, the intermediate conductor, and the dielectric member can be produced by simple, inexpensive manufacturing processes.